Basketball scouts mystify Mychal Thompson, the NBA’s first overall pick in 1978 with the Blazers who won two titles with the Lakers.

One of his sons, shooting guard Klay Thompson, became a lottery pick by the Warriors in the 2011 NBA Draft. Klay, and his drop-dead 3-pointer, became one of the NBA’s top rookies last season.

Another son, Mychel, out of Pepperdine, didn’t get selected in the same draft. He started last season on the Knicks’ D-League team, the Erie Bayhawks, before getting a shot with the Cavaliers. He appeared in five games, making three starts.

“Today’s NBA scouts mostly look at athletes rather than basketball players,’’ Mychal Thompson told The Post. “They don’t look at guys who understand how to play the game of basketball. It always puzzles me, the guys who really understand how to play and have high basketball IQs. The Spurs take those guys, but far too many scouts don’t value that anymore.’’

The Knicks apparently do. That’s why Mychel Thompson — at assistant general manager Allan Houston’s insistence — is headed to Knicks training camp that opens in one week. The 6-foot-7 shooting guard has a legitimate shot to make the team. One scout said he can now shoot it all the way to the 3-point line. The 24-year-old will compete against guard Chris Smith, forward Chris Copeland and John Shurna for the 14th and 15th spots.

Thompson played on the Knicks’ summer team in Las Vegas, averaging 5.6 points and 3.4 rebounds in 20 minutes. Houston also is the Erie GM and saw a lot of Thompson.

“[The Knicks] are a good opportunity,’’ said Mychal Thompson, the Lakers radio analyst for 10 years. “He’s a 6-7 big guard — one position they are in search of with the [knee] injuries to Iman Shumpert. Mychel is capable of stepping in and providing what they need at the 2 guard, defensively. Allan wanted him at camp because he also knew how to play the game.’’

As far as comparisons to Klay, the senior Thompson said: “Klay is more scoring-minded. That’s the difference. Klay wants to be a scorer, like Kobe [Bryant] and [Dwyane] Wade. Mychel is more apt to let his teammates take over the scoring load. But Mychel is better getting to the rim. He’s bigger and stronger than Klay.’’

All three of Thompson’s sons are pro athletes. The youngest, Trayce, 21, is a baseball player who was a second-round pick by the White Sox two years ago and advanced from Single-A to Triple-A in his first full season. Trayce also doesn’t see much difference between Klay and Mychel, other than Klay’s 3-point shooting.

“Mikey is just as physically talented, not as gifted a shooter, but more athletic, stronger and more vertical ability than Klay,’’ Trayce said. “Mikey always beat Klay 1-on-1 in high school. … Mikey cared too much about his teammates in college scoring and it damaged his personal stats. I always felt you put him on the court with the NBA’s best guys, he can look like he belongs…. He has just as much as talent as Klay, and Dad and Klay tell him that.’’

Santa Margarita Catholic coach Jerry DeBusk, who just retired after 20 years, coached the three Thompson brothers. He raved about the boys’ parents, including 5-foot-10 Julie, a former volleyballer at San Francisco.

“I wish they were all like Mychal and Julie Thompson,’’ DeBusk said. “I never talked basketball with Mychal. He wasn’t one of those parents who came in and asked why my kid wasn’t playing more.’’

“All three boys are very competitive with each other, driven to success and put in the work,’’ added DeBusk, who won a state title with Klay and Trayce. “I saw Mychel improve so much at Pepperdine. They’re the crème de la crème. All three looked up to dad and his accomplishments. That was kind of who they aspired to be.’’